1. Field of the Invention
The present invention relates to a color photographic light-sensitive material, and more particularly relates to a color photographic silver halide light-sensitive material capable of forming yellow color images having an increased image density and a reduced fog density.
2. Description of the Prior Art
The step or steps of forming cyan, magneta and yellow dyes by coupling dye-forming couplers with the oxidation products of aromatic primary amine color developing agents which are produced by the reaction with exposed silver halide particles have generally been used for the formation of color photographic images.
As the yellow dye-forming couplers capable of forming yellow color images having an absorption in the wave length of about 400 to 500 m.mu., .beta.-ketoaceto acetic acid esters, .beta.-diketones, N,N'-malondiamides and .alpha.-acylacetoamides are known. Of these couplers, the acylacetoamides have been widely used as yellow dye-forming couplers in the art since they have better characteristics.
Further, .alpha.-acylacetoamides of which an active hydrogen atom in the .alpha.-position is substituted with a coupling-off group have been proposed.
The .alpha.-acylacetoamides (substituted in the .alpha.-position) can reduce an amount of silver halide added to the light-sensitive material because they require only two equivalents of silver halide as an oxidizing agent for forming a molecule of dye (therefore, they are generally designated "two equivalent couplers"). In addition, image sharpness is increased because these couplers reduce light-scattering in the light-sensitive material.
Further, since the dye is formed in the color developing steps using .alpha.-acylamide type couplers (substituted in the .alpha.-position), it is unnecessary to use a specific oxidizing agent after the color development and the color developing steps are easily simplified.
However, this coupler has the defect that increased yellow fog is often generated, and this defect is an obstacle in using the couplers in light-sensitive materials.
In order to remove this defect, the use of a compound capable of forming a slightly soluble silver salt such as an active sulfur compound, the use of an insufficiently spectrally sensitized silver halide emulsion, the use of weak developing conditions, and the use of colorless competing couplers have been proposed. However, these methods are not sufficient because the sensitivity of the light-sensitive material is adversely reduced, the shelf life of the light-sensitive material is shortened, the developing time is increased and unstable color dye images are formed.
In order to prevent color fog, it is well known to carry out color development in the presence of a reducing compound, and many useful reducing compounds are proposed. For example, dialkylhydroquinones are disclosed in U.S. Pat. Nos. 2,336,327, 2,360,290, 2,403,721, 2,728,659, 2,732,300 and 2,735,765, hydroquinones substituted with an aryl group are disclosed in U.S. Pat. No. 2,418,618, hydroquinones substituted with a sulfo group are disclosed in U.S. Pat. No. 2,675,314, high molecular compounds having a hydroquinone residue are disclosed in U.S. Pat. No. 2,360,290, catechol derivatives are disclosed in French Pat. No. 885,982, aminophenol derivatives are disclosed in U.S. Pat. Nos. 2,336,327, 2,403,721 and British Pat. No. 1,133,500, gallic acid derivatives are disclosed in Japanese Pat. Publication No. 13,496/68 and U.S. Pat. No. 3,457,079, and ascorbic acids are disclosed in U.S. Pat. Nos. 2,360,290 and 2,384,658. However, it has now been determined by our experiments that none of these compounds remove or control the color fog to a sufficient degree.
Moreover, when a silver halide emulsion layer of the so-called multi-layer type light-sensitive material, which is composed of a support having coated thereon light-sensitive silver halide emulsion layers sensitive to different spectral regions and containing one of the couplers, the oxidation product in one layer can diffuse into another layer, whereby the relation between the spectral sensitivity of the layer and the dye formed therein is destroyed. Therefore, the phenomenon is not preferred for the color reproduction because of color mixing. Previously, proposals of means to correct the mixing of couplers have been made, but these means are not suitable since they have little effect on the couplers or they have an adverse influence on the stability of color images.
An object of this invention is to provide a color photographic material having high sensitivity and capable of forming higher image density without causing color fog on color development.
A second object of the invention is to provide a color photographic material which is stable for a long period of time between the preparation thereof and the development thereof.
A third object of the invention is to provide a color photographic light-sensitive material capable of forming sharp color photographs with stable color images and with better reproduction of white color.
A fourth object of the invention is to provide a color photographic light-sensitive material capable of being rapidly developed without decreasing the image qualities.
These and other objects of the invention will be apparent from the following disclosure.